Phase change materials (PCMs) offer great potential as a latent heat energy storage technique to provide energy ef?cient systems in new and existing residential buildings. Due to their unique characteristic of high storage densities and latent heat properties, PCMs provide opportunities for greater energy storage in many applications for residential buildings including space heating/cooling. This paper aims to understand the potentials of applying PCM-system (Paraffin waxes and Salt hydrate) in harsh hot climate, assessing the effects of employing it on the thermal behavior of building applying the PCM based pre-cooling system and providing recommendations regarding the design and implementation of PCM in building. In this study PCM based air pre-cooling concept will be examined and evaluates its performance in extremely hot climate of UAE. The drop in the outlet air temperature of the duct system quantifies the cooling effect. A paraffin waxes and salt hydrate is characterized. A paraffin based PCM with melting range of 30-33°C was selected for its preferable properties and integrated in containers placed in the test chamber mimic the air conditioning duct system, and its cooling effect is monitored. A Conjugate heat transfer model employing enthalpybased formulation is developed to predict the optimized PCM container size and optimum airflow rate validated with experimental data. Single and series columns of PCM containers subjected to different levels of supplied air velocity at range of 1 m/s - 4m/s are evaluated. Employing series of PCM enclosures at low air velocity of 1m/s enhanced the pre-cooling performance and reduced the outlet air temperature to 35°C yielding a temperature drop up to 11°C.